1. Field of the invention
This invention relates generally to a system for remotely controlling, for example, a television receiver, and more particularly to a combination of an improved transmitter for transmitting a remote control signal and an improved receiver for receiving the remote control signal adapted to control, for example, a television receiver.
2. Description of the Prior Art
In the art, when a plurality of functions such as ON and OFF operation of an electric power source for a television receiver, its volume adjustment, channel selection and so on are remotely controlled, a plurality of supersonic remote control signals with different frequencies are generally used, in which the frequencies of the remote control signals are made to correspond with control commands. In such a prior art remote contol system, due to the limit or restriction of frequency characteristics of a converting system which converts a supersonic wave transmitted as a control signal into an electric signal, various kinds of control commands can not be transmitted and received. Further, if a number of frequencies are used in a limited frequency range so as to transmit and receive a number of control commands, distances between the frequencies are narrowed and hence there may be a fear that an error operation or misoperation is caused.
To avoid such an error operation, it is desired that, in the remote control system, a transmitted control signal is made to have a single frequency and to be an intermittent signal as a pulse to discriminate the control command by the pulse width or the number of the pulses. Such a type of a remote control system is already proposed now. However, when a pulse signal with a predetermined number or pulse width is transmitted for an instrument such as a television receiver, which is to be controlled, to achieve a predetermined operation, if the number of pulses or the pulse width deviate from the predetermined conditions by, for example, a loose contact of a switch, the misoperation of a transmitter, the affect of a reflected wave and so on, there may be a fear that a misoperation is caused.